U.S. Pat. No. 4,270,806 discloses a brake system having combined hydraulic and regenerative braking for an electrically powered vehicle. In this brake system a mix occurs between the hydraulic and regenerative braking at lower braking efforts, but for all braking efforts above a specified hydraulic line pressure, braking is entirely hydraulic. In addition, the regenerative contribution decreases for increasing braking effort in a lower range of line pressures. This reduction or elimination of regenerative braking is both undesirable and unnecessary. Disposing of the kinetic energy of vehicle motion by dissipating heat in friction braking pads is wasteful of our precious energy resources. While it can not be altogether avoided such wastefulness should be reduced as far as possible. Further, this brake system makes no provision for the incorporation of an anti-skid feature which is a safety feature desired by may customers.
U.S. Pat. No. 4,850,650 discloses an anti-skid braking system having both a high level supervisory control and a low level (local) control. The low level control attempts to maintain the individual wheel performance near that commanded by the high level and the high level attempts to optimize overall braking performance, e.g., by distributing the braking effort between the front and rear wheels based on dynamic front and rear axle weights.
U.S. Pat. No. 5,222,787 discloses an electro-hydraulic braking system having an electronic control which separates the front and rear braking efforts. This brake system is a basis for the for the present invention and reference may be had thereto for some of the details of the electro-hydraulic portion of the braking system of the present invention.